Effectiveness of Percutaneous Balloon Mitral Valvuloplasty for Rheumatic Mitral Stenosis with Mild to Severe Mitral Regurgitation

This study is designed to test whether percutaneous balloon mitral valvuloplasty (PBMV) is effective for rheumatic mitral stenosis in Chinese patients with moderate to severe mitral regurgitation. Fifty-six patients with rheumatic mitral valve stenosis were divided into the mild, moderate, and severe regurgitation groups. Cardiac ultrasonography was measured before and 1 to 2 days after PBMV. Following PBMV, the mitral orifice was enlarged, and the left atrial diameter was reduced in the 3 patient groups. The enlargement of the mitral orifice in the mild regurgitation group was greater than that observed in the moderate and severe regurgitation groups. The size of the regurgitation area increased in the mild regurgitation group and decreased in the moderate and severe regurgitation groups, with the decrease in the severe regurgitation group being greater than that in the moderate regurgitation group. Therefore, PBMV is effective for treating rheumatic mitral stenosis in Chinese patients with mild to severe mitral regurgitation

Dependence of Thermal Stability on Molecular Structure of RAFT/MADIX Agents : A Kinetic and Mechanistic Study

The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., ?-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the ?-elimination of thiocarbonylthio compounds possessing ?-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (E)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more ?-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) ?CH2Ph (5) > ?PS (PS-RAFT 15) > ?C(Me)HPh (2) > ?C(Me)2C(═O)OC2H5 (7) > ?C(Me)2Ph(1) > ?PMMA (PMMA-RAFT 16) > ?C(Me)2CN (6). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of O-ethyl (11) > ?N(CH2CH3)2 (13) > ?SCH(CH3)Ph (8) > ?Ph (2) > ?CH2Ph (4) > ?PhNO2 (3). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated. The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., ?-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the ?-elimination of thiocarbonylthio compounds possessing ?-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (E)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more ?-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) ?CH2Ph (5) > ?PS (PS-RAFT 15) > ?C(Me)HPh (2) > ?C(Me)2C(═O)OC2H5 (7) > ?C(Me)2Ph(1) > ?PMMA (PMMA-RAFT 16) > ?C(Me)2CN (6). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of O-ethyl (11) > ?N(CH2CH3)2 (13) > ?SCH(CH3)Ph (8) > ?Ph (2) > ?CH2Ph (4) > ?PhNO2 (3). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated

Dependence of Thermal Stability on Molecular Structure of RAFT/MADIX Agents: A Kinetic and Mechanistic Study

The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., β-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the β-elimination of thiocarbonylthio compounds possessing β-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (<i>E</i>)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more β-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) −CH₂Ph (<b>5</b>) > −PS (PS-RAFT <b>15</b>) > −C(Me)HPh (<b>2</b>) > −C(Me)₂C(O)OC₂H₅ (<b>7</b>) > −C(Me)₂Ph(<b>1</b>) > −PMMA (PMMA-RAFT <b>16</b>) > −C(Me)₂CN (<b>6</b>). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of <i>O</i>-ethyl (<b>11</b>) > –<i>N</i>(CH₂CH₃)₂ (<b>13</b>) > –<i>S</i>CH(CH₃)Ph (<b>8</b>) > −Ph (<b>2</b>) > −CH₂Ph (<b>4</b>) > −PhNO₂ (<b>3</b>). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated

Direct access to pyrido/pyrrolo[2,1-b]quinazolin-9(1H)-ones through silver-mediated intramolecular alkyne hydroamination reactions

We report a synthetic methodology for the construction of the fused heterocyclic compounds pyrido[2,1-b]quinazolin-9(1H)-ones and pyrrolo[2,1-b]quinazolin-9(1H)-ones through an AgOTf-catalyzed intramolecular alkyne hydroamination reaction. The methodology is applicable to a wide scope of substrates and produces a series of fused quinazolinone heterocycles in good to excellent yields

Au(I)/Ag(I)-Catalyzed Cascade Approach for the Synthesis of Benzo[4,5]imidazo[1,2‑<i>c</i>]pyrrolo[1,2‑<i>a</i>]quinazolinones

An efficient and facile Au­(I)/Ag­(I)-catalyzed cascade method has been developed for one-pot synthesis of the complex polycyclic heterocycles benzo­[4,5]­imidazo­[1,2-<i>c</i>]­pyrrolo­[1,2-<i>a</i>]­quinazolinone derivatives through treatment of the substituted 2-(1<i>H</i>-benzo­[<i>d</i>]­imidazol-2-yl)­anilines with 4-pentynoic acid or 5-hexynoic acid. The strategy features a Au­(I)/Ag­(I)-catalyzed one-pot cascade process involving the formation of three new C–N bonds in high yields, and with broad a substrate scope

Au(I)/Ag(I)-Catalyzed Cascade Approach for the Synthesis of Benzo[4,5]imidazo[1,2‑<i>c</i>]pyrrolo[1,2‑<i>a</i>]quinazolinones

An efficient and facile Au­(I)/Ag­(I)-catalyzed cascade method has been developed for one-pot synthesis of the complex polycyclic heterocycles benzo­[4,5]­imidazo­[1,2-<i>c</i>]­pyrrolo­[1,2-<i>a</i>]­quinazolinone derivatives through treatment of the substituted 2-(1<i>H</i>-benzo­[<i>d</i>]­imidazol-2-yl)­anilines with 4-pentynoic acid or 5-hexynoic acid. The strategy features a Au­(I)/Ag­(I)-catalyzed one-pot cascade process involving the formation of three new C–N bonds in high yields, and with broad a substrate scope